I’m having problems opening some projects created in Cubase 5 (not sure exactly what version), basically they crash C6 when loading, so I want to install 5.5 and see if I can open them there.
Will this be a straight install or do I need to do anything special?
They are two different programs that can run alongside without a problem, license included: your Cubase 6 license allows you to use all the previous versions.
Just backup your preferences and presets, just in case. Take a look in the “Where are the settings stored?” section under the “Customizing” chapter in Cubase 6’s manual.